Filter element and filter system

ABSTRACT

A filter element has of a filter medium ( 10 ) folded in a zig-zag manner and designed in a tubular shape. End plates ( 11, 12 ) are arranged on the filter medium end faces. End plate ( 12 ) has a concentric opening as well as a first annular ring ( 14 ) and a second annular ring ( 15 ), and a sealing groove ( 16 ) arranged between the rings. A reinforcement plate ( 17 ) is arranged at the end plate and has an annular surface ( 23 ) extending in axial direction across folds of the filter element.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 12/680,978 filed Jun. 21, 2010, the entire disclosure of whichis incorporated herein by reference. U.S. Ser. No. 12/680,978 is a USNational Stage Entry of international patent application no.PCT/EP2008/063202, filed Oct. 2, 2008 designating the United States ofAmerica, the entire disclosure of which is incorporated herein byreference. Priority is claimed based on Federal Republic of Germanypatent application no. 20 2007 013 822.9, filed Oct. 2, 2007.

TECHNICAL FIELD

The invention concerns a filter element and a filter system, especiallyfor the intake air of an internal combustion engine.

PRIOR ART

U.S. Pat. No. 4,720,292 discloses an air filter having the followingfeatures: a housing with an axial outlet opening and a substantiallyopen second end that is closable by a removable cover. On thecircumference of the housing an air inlet opening is arranged. In thehousing, there is a substantially cylindrical filter element with aninternal support tube, a filter with an external support tube, whereinthe filter element is coaxially arranged in the housing. The sealingaction of the filter element on the housing is realized by an annularend plate that has a substantially cylindrical radially inwardlyoriented surface and is pushed over an inner section of the outlet part.

It is well known that the filter inserts of air filters are exchangedafter a certain operating time. Depending on the dust load, the servicelife of an air filter can be a few days (construction machinery) up toseveral months.

The filter insert disclosed in the aforementioned U.S. patent as well asother conventionally employed filter inserts are comprised of acombination of materials wherein, in particular for the support tubes,sheet steel or plastic material is used. The filter medium is paper or aplastic nonwoven fabric. The end plates are comprised of plasticmaterial, for example, of a soft elastomer.

Especially in case of frequent exchange of filter elements the reliableand process-safe sealing action of the filter element in a housing isimportant. The sealing action should be temperature-resistant andvibration-resistant. Even in facilities or devices that are exposed tostrong vibrations or shocks, the sealing action of the filter elementmust be ensured. At the same time, the filter element itself howevershould have, if possible, no metallic elements so that it can bedisposed thermally without problems.

SUMMARY OF THE INVENTION

The invention has therefore the object to provide a filter element and afilter system with a high filtration property and a reliable sealingaction between the area of the unfiltered and the area of the filteredmedium. This object is solved by the features of the independent claim.

The decisive advantage of the invention resides in that by theconfiguration of the seals of the filter element with two annularbead-shaped arrangements and an intermediately positioned sealing grooveit is ensured that, on the one hand, a high sealing action and, on theother hand, a good support action of the filter element in a housing areprovided. Especially in case of use of plastic material for the sealingaction on vibration-loaded elements, a design is required that functionsreliably even in case of extreme temperature fluctuations.

According to one embodiment of the invention, the end plate thatsupports the seal is comprised of polyurethane. Of course, there is alsothe possibility to manufacture the end plate of a soft elastomer or ofseveral components, for example, by an in-mold assembly injectionmolding process, wherein the component that forms the seal is comprisedof an elastomer and the component that produces the connection to thefilter medium is a thermoplastic material. The latter can be welded orglued to the filter medium.

In a further embodiment of the invention, it is proposed to provide thereinforcement plate that is arranged within the end plate withperforations These perforations enable penetration of polyurethaneduring manufacture of the filter element and produce in this way anintimate, positive-locking connection between filter medium and sealingcontour and reinforcement plate.

According to a further embodiment the reinforcement plate is provided inthe area that extends past the polyurethane foam with an annular surfaceor a cylindrical annular wall. It extends across the folds of the filtermedium, for example, across an area of 0 to 30% of the total length ofthe filter element and protects thus the folds in case of improperhandling or, for example, when knocking off dirt or manually cleaning ofthe filter element.

According to one embodiment of the invention, the second end plate thatis positioned opposite the sealing end plate can also be comprised ofpolyurethane foam and has a closure member made of a thermoplasticmaterial that seals the interior of the filter element.

The end plates can be produced also by a thixotropic application method.This means a metered application of the thixotropic material whereinsimultaneously the sealing structure is formed without additional molds.

The invention concerns also a filter system with a filter element. Thisfilter system serves in particular for filtration of the intake air ofan internal combustion engine and is comprised of a housing and a coverfor receiving the filter element. Advantageously, the filter system isprovided with two annular grooves that in the area of the sealing actioncommunicate with the sealing contours of the filter element.

According to a further embodiment, on the housing in the area of theinlet a cyclone or rotary flow separator is provided. It is comprised ofa guiding geometry that imparts a rotational movement to the medium. Bymeans of this rotation the dirt is concentrated in the area of thehousing wall and is removed at a suitable location by means of a dirtoutlet.

According to a further embodiment of the invention, a secondary elementis provided that is positioned in the interior of the filter system. Thesecondary element has the task to maintain the outlet of the filtersystem closed upon exchange of the filter element so that no dirt canpenetrate into this area while the filter element is cleaned orreplaced. The secondary element in a preferred embodiment is connectedby means of a screw connection to the housing and provided with a sealrelative to the housing.

These and further features may not only be taken from the claims, butalso from the figure description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in the following with the aid of anembodiment in more detail. It is shown in:

FIG. 1 a section view of a filter system and

FIG. 2 a detail illustration in the sealing area of the filter housing.

The filter system according to FIG. 1 is comprised of a housing 26 thatis substantially concentrically configured and has an inlet 28. Thefilter system serves for filtration of the intake air of an internalcombustion engine. Through the inlet 28 the air to be purified issupplied according to arrow 38, flows through the cyclone preseparator34 and a rotary flow is imparted. As a result of this rotary flowparticles that are contained in the air reach the housing wall and arecarried from there to the exterior through a dirt outlet 35 that may beclosed off by a suitable valve.

EMBODIMENT(S) OF THE INVENTION

On the housing 26 a middle section 37 is arranged. The latter is alsodesigned concentrically and is coupled to the housing in the area 40,for example, by means of a weld. On the middle section 37 there is acover 27. The latter is detachably connected to the middle section bymeans of clamping closures or another suitable closure system. Cover,middle section, and housing together thus provide a closed system thathas an outlet 29 for discharging the purified air.

Inside the complete system there is a filter element 39. The latter iscomprised of a zigzag-folded filter medium 10 and is of a concentricshape. The end faces of the filter element 39 have end plates 11, 12.While one end plate 12 has a concentric opening 13, the other end plate11 is provided with a closure member 24. It is also possible to providethe additional end plate with a concentric opening that is closed off bya socket at the cover 27. The air to be purified flows according toarrow 41 through the filter element and, purified, according to arrow 42through the outlet 29 to an internal combustion engine, not illustratedhere. The filter element is provided at the end plate 12 arranged to theright with a first annular bead 14 and a second annular bead 15. Betweenthem there is a sealing groove 16.

Inside the end plate 12 a reinforcement plate 17 is provided that hasperforations 22. The reinforcement plate in the outer area, i.e.,outside of the sealing compound area, is provided with an annularsurface 23. It serves for shielding the filter medium or the elementduring assembly or knocking off dirt or other manipulations by hand.

The annular bead 14 as well as the annular bead 15 abut ribs 20, 21 anddefine thus the axial position of the filter element in the housing.

In an alternative embodiment that is not limited to this example, theposition of the filter element can be defined by engagement of theannular beads 14 and 15 in annular grooves 31 and 32 without abuttingthe ribs 20, 21. Alternatively, other points can be used for additionalaxial and/or radial fixation.

The ribs are disclosed in detail in FIG. 2; they are so-called doubleribs, i.e., two neighboring ribs 20 a, 20 b, 20 c that are arranged atthe groove bottom of annular groove 31 and at the bottom of the annulargroove 32 are arranged and, for example, have a height of 3 to 6 mm.

The sealing stay 33 that is located between the two annular grooves hasat its flanks the sealing area; here, the end plate 12 seals with itssealing groove 16. In this way, a double sealing principle by means ofthese two flanks is provided. The sealing groove 16 is slightly deeperthan the sealing stay 33 so that a certain axial tolerance in this areais possible. As already mentioned, the end plate is comprised ofpolyurethane foam or another elastomer whose hardness is selected suchthat, on the one hand, the end plate can provide the required sealingforces and, on the other hand, it also ensures a good positioning actionof the filter element in the filter housing. Because of the two-flanksealing action and the support of the annular beads 14, 15 on the ribs20 a relatively minimal mounting force and also a minimal release forcefor exchanging the filter element are required.

In an alternative embodiment that is not limited to this example, thesealing stay 33 has at its axial end an additional sealing bead, forexample, an annular structure that is extending on the sealing stay 33and is oriented axially into the interior of the housing. In this way,an additional axial sealing action can be achieved—without greatinfluence on the pressing force upon insertion of the filter elementinto the filter housing. This can be realized, for example, by a sealingbead that is thin in comparison to the sealing stay 33.

The end plate 11 is provided with support noses 43, 44. They aresupported on the cover 27 and in this way ensure a satisfactory axialforce in the direction of the end plate 12 and thus a reliable sealingaction. In the end plate 12 a closure member 24 is embedded. Itseparates the raw air chamber from the filtered air chamber. Within thefilter element there is a secondary element 36 that surrounds theinterior 25. The purified air flows through the secondary element thatconventionally is provided with a nonwoven fabric cover 45. The nonwovenfabric cover is attached to a thermoplastic or metallic base member 46.The secondary element 36 is attached by means of a thread 47 to theoutlet socket of the outlet 29 and at the same time is sealed by meansof an O-ring 48 in this area.

The housing 26 is provided with an inner wall 49. This inner wall has aminimal spacing relative to the annular surface 23. On the inner wall aclamping element 50 according to FIG. 3 is provided.

This clamping element is comprised of spring steel that is shaped atseveral locations and projects into the mounting space of the filterelement. The shaped locations are shown in FIG. 1 and identified byreference numeral 51. Upon insertion of the filter element the shapedlocations are forced outwardly and serve for centering the filterelement. Inasmuch as a filter element without the annular surface 23 isinserted into the housing, there is no possibility for centering thefilter element. In this case, possibly the filter element or filtermedium would be damaged. Therefore, the clamping element serves as aprotection against accidental mounting of a wrong or faulty filterelement.

1. A filter element, comprising: a zigzag-folded filter medium (10)arranged in a tubular concentric shape; a first end plate (11) arrangedat an axial end face of said concentric filter medium, said first endplate having a central portion that is either open or closed; and asecond end plate (12) arranged at an opposing axial end face of saidfilter medium; wherein said second end plate (12) includes a concentricopening (13) therethrough, said second end plate extending substantiallyin a circular ring-shape about end face folds of the filter medium;wherein said second end plate (12) includes an outwards facing ring faceincluding a first annular bead (14) extending axially outwards from saidsecond end plate in a direction axially away from said filter element;wherein the second end plate (12) further includes a reinforcement plate(17) arranged at said opposing axial end face in an area between thesaid filter medium end face and said annular bead, wherein thereinforcement plate has an annular surface (23) extending in axialdirection outwardly across the filter element.
 2. The filter elementaccording to claim 1, wherein said annular surface (23) is operable tocenter said filter element with a filter housing configured to receivesaid filter element by engaging against a clamping element (50) providedon an inner wall of said filter housing.
 3. The filter element accordingto claim 1, wherein said outwards facing ring face of said second endplate (12) includes a sealing groove (16) formed in said ring face. 4.The filter element according to claim 3, wherein said second end plate(12) has a second annular bead (15) extending axially outwards from saidsecond end plate (12) in a direction axially away from said filterelement, said second annular bead (15) concentrically spaced from saidannular bead (14).
 5. The filter element according to claim 4, whereinsaid annular beads have facing sidewalls defining said sealing groove(16) therebetween.
 6. The filter element according to claim 1, whereinsaid annular bead (14) includes at least one outer end face (18, 19),said at least one outer end face (18,19) is configured to besupportively received against support ribs (20,21) provided in a housingconfigured to receive said filter element.
 7. The filter elementaccording to claim 1, wherein said second end plate (12) is comprised ofpolyurethane foam or an elastomer.
 8. The filter element according toclaim 7, wherein said reinforcement plate (12) extends past saidpolyurethane foam of said second end plate with an annular surface or acylindrical annular wall.
 9. The filter element according to claim 8,wherein said extending reinforcement plate (12) extends across andoverlays folds of a radially outwardly side of said filter medium. 10.The filter element according to claim 9, wherein said reinforcementplate overlaying said outwardly side extends across 0 to 30% of a totallength of said filter element and protects thus said folds againstknocking or impact such as due to knocking off dirt or manually cleaningof said filter element.
 11. The filter element according to claim 7,wherein said reinforcement plate has perforations (22) operable tosupport flow of polyurethane foam providing a positive-lockingconnection between said filter medium and said reinforcement plate. 12.The filter element according to claim 1, wherein said first end plate(11) is comprised of polyurethane foam and has a concentrically arrangedclosure member (24) that seals an interior space (25) of the filterelement (10) in the area of said first end plate.
 13. The filter elementaccording to claim 1, wherein said first end plate includes an outwardsfacing ring face including a first annular bead extending axiallyoutwards from said first end plate in a direction axially away from saidfilter element; a second annular bead extending axially outwards fromsaid first end plate in a direction axially away from said filterelement, said second annular bead of said first end plate concentricallyspaced from said first annular bead of said first end plate; whereinsaid annular beads of said first end plate have facing sidewallsdefining a sealing groove therebetween on said first end plate.
 14. Afilter system with a filter element according to claim 1, comprising: afilter element according to claim 1; a housing (26) that issubstantially concentrically configured relative to said filter elementsaid configured to receive said filter element therein; a cover (27)closing off said housing (26) and also concentrically configured; aninlet (28) arranged on said housing and/or said cover, said inletconfigured to supply medium to be filtered to said filter element; anoutlet concentrically arranged on said housing (26) and configured todischarge filtered medium from said housing; and a sealing contourprovided on an inner surface of said housing, said sealing contoursealably matching at least one of the said sealing beads (14,15) andsaid sealing groove (16).
 15. The filter system according to claim 14,wherein said sealing contour on said housing is comprised of twoconcentric axially extending annular grooves (31, 32); and a sealingstay ring (33) is arranged between said two annular housing grooves;wherein said annular grooves at a groove bottom include radiallyextending ribs (20, 21) extending across said housing grooves; andwherein said sealing stay (33) has a height that is less than height ofsaid sealing groove (16) of said filter element.
 16. The filter systemaccording to claim 14, wherein said housing (26) is includes with aninner wall (49); wherein a clamping element (50) is provided on saidinner wall; and wherein said clamping element (50) engages against saidannular surface (23) of said reinforcement plate, centering said filterelement upon insertion into said housing (26).
 17. The filter systemaccording to claim 14, further comprising: a cyclone preseparator (34)is arranged inside said housing between said housing and said filterelement; and a dirt outlet (35) is arranged on said housing (26) or onsaid cover (27).
 18. The filter system according to claim 14, furthercomprising: a secondary element (36) arranged inside and secured intosaid housing, said secondary element arranged at an interior of thefilter element, said secondary element closing of said outlet of saidhousing with a filter media during removal or exchange of said filterelement.
 19. The filter system according to claim 18, wherein saidsecondary element (36) is secured to said housing (26) by a threadedconnection.